Remove %clean section

None of currently supported distributions need that.
Last one was EL5 which is EOL for a while.

Signed-off-by: Igor Gnatenko <ignatenkobrain@fedoraproject.org>

perl-Digest-MD4.spec

@@ -56,9 +56,6 @@ find %{buildroot} -type f -name '*.bs' -empty -delete
 %check
 make test
 
-%clean
-rm -rf %{buildroot}
-
 %files
 %doc Changes README rfc1320.txt
 %{perl_vendorarch}/Digest/